package com.hmdp.utils;

import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.swing.text.DateFormatter;
import java.text.DateFormat;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;

/**
 *  全局唯一ID生成器
 */

@Component
public class RedisIdWorker {

    /**
     * 开始时间戳：设置为2022-1-1  00：00：00
     */
    private static final long BEGIN_TIMESTAMP = 1640995200L;

    private static final int COUNT_BITS = 32; // 序列号的位数

    private StringRedisTemplate stringRedisTemplate;

    public RedisIdWorker(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    /**
     * 获取ID
     * @param keyPrefix  业务模块前缀
     * @return
     */
    public long nextId(String keyPrefix) {
        // 1.生成时间戳
        // 1.1 获取当前时间戳
        LocalDateTime now = LocalDateTime.now();
        long nowSecond = now.toEpochSecond(ZoneOffset.UTC);
        // 1.2 当前时间戳 - 开始时间戳
        long timeStamp = nowSecond - BEGIN_TIMESTAMP;

        // 2.生成序列号
        // 2.1获取当前日期格式：20221203
        String date = now.format(DateTimeFormatter.ofPattern("yyyy:MM:dd"));
        // 2.2自增长
        Long count = stringRedisTemplate.opsForValue().increment("icr:" + keyPrefix + ":" + date);

        // 3.拼接并返回格式 ：符号位----------时间戳-------------------   -----------序列号------------------
        //                  0 - 00000000 00000000 00000000 0000000 - 0000000 00000000 00000000 00000000

        return timeStamp << COUNT_BITS | count;
    }


    /*
    public static void main(String[] args) {
        LocalDateTime time = LocalDateTime.of(2022, 1, 1, 0, 0, 0);
        long second = time.toEpochSecond(ZoneOffset.UTC);
        System.out.println(second);  // 获取一个初始值
    } */

}
